10 Answers
10

I'm attracted by the argument made here, that it's to do with trams, given that both "off his trolley" and "off his rocker" appear in print around the same time. I also feel the fact that all the early citations are about "going off your rocker" or "being driven off your rocker" - rather than falling/running/getting - suggests it's the same as "going off the rails".

@Mark: Probably pointing out that if you're "off your rocker", you're unstable (i.e. as a rocking chair would have to be for someone to fall off of it).
–
Billy ONealDec 19 '10 at 10:18

I don't think falling off a rocking chair suggests instability. It more suggests misfortune, like coming off a wild bull ride.
–
MarkDec 19 '10 at 16:07

Don't misapprehend. The rythm of metrical rocking (lulling) is universally a symbol, as well as reality per se, of peace of mind--agitating of a sort within limits, in a confined (seemingly secured) environment. Rocking, or absence thereof, extends from the maternal bosom whether near birth or (figuratively) near the mental/emotional collapse in death.
–
lexOct 19 '12 at 23:19

This is more speculation than anything, but it's somewhat stereotypical for older people back in the day to be sitting on rocking chairs and just passing the time, right? What if the phrase originally didn't mean to suggest that someone merely is crazy, but also outwardly displaying it? A crazy person might feel the urge to get out of their chair, run around and act mad, whereas a more mild mannered one would just quietly rock back and forth and not cause a scene.

This possibility certainly comes to mind, but there's also another one: that you fall off your rocker, and hit your head real hard, getting a brain damage and becoming crazy. As you say, speculation.
–
RegDwigнt♦Dec 19 '10 at 10:19

That's a good one too. Either it's easy to retcon a meaning into any phrase, or the very reason specific terms became common in the first place is because they're easy enough to grasp if you had to come up with your own explanation.
–
Joost SchuurDec 19 '10 at 10:27

1765 is another possible first in another vein: Mother Goose and rocker association with lulling, or casting out of being lulled, one would suppose, might likewise be a metaphor for the passage forward from baby hood...or, possibly, back into earlier babyhood...and figurative need of lulling ...in the sense, respectively, of mental/emotional maturation or regression.

If only the cited authors in above-cited instances of rocking-chair/rocker association with mental disturbance were alive to be asked (if they based their allusion on familiarity with the rhyme, Rockaby Baby (in the treetops...when the bough breaks down will come baby, [rocking] cradle and all), their answers might come closer to definitively answering the whence and wherefore.

"Rock-a-bye baby, on the treetop, When the wind blows, the cradle will rock, When the bough breaks, the cradle will fall, And down will come baby, cradle and all." That's the version I heard when I was a wee nipper. When you think about it, though, what happened to that poor baby is kind of frightening, isn't it? The same goes for the children's nighttime prayer I grew up reciting, ". . . if I should die before I wake, I pray thee, Lord, my soul to take"!
–
rhetoricianAug 7 '13 at 15:25

A more interesting topic than first meets the eye!! The phrase first came to light around 1896, and there are 2 schools of thought as to its original reference and meaning:

School one: The "rocker" was the metal strip which held the long metal arms of electric trolleys onto their track. I remember Halifax in the early 1960s still had them - pretty comical when the conductor had to get off in all kinds of weather to manoever the arm back onto its "rocker"!! Here's a quotation from the first source below: "......the first appearance in print of OFF ONE’S TROLLEY in 1896 (see quote below) was followed less than one year later in 1897 (see quote above) by OFF ONE’S ROCKER. This, and the fact that electric trolleys were ‘off’ and running in the 1890s would seem to indicate that we might have more than just a coincidence here. And it strikes me that falling ‘asleep’ in one’s rocking chair is a much more likely event than ‘falling off one’s rocking chair’ – an occurrence seemingly too rare to warrant having an expression named after it – or the even rarer occurrence of somehow being ‘off the rocker’ on one’s rocking chair (whatever that might mean – it’s hard to visualize). On the other hand, even by the 1940s when I would pass three different trolley lines on my mile or so walk to my elementary school every day (yes, kids actually walked to school in those prehistoric times), I often saw men working on a stalled trolley trying to get that overhead, spring-loaded pole, back onto the power line where it belonged – it had gone OFF ITS ROCKER. "

School two (referred to above also): " Originally the phrase was specifically about what we'd now call "mood swings." Now it means "to be crazy," but it used to connote a "normal" person who periodically, and unexpectedly, goes crazy.

"Aw, he's just off his rocker-- it'll pass."

Just imagine the kind of person you'd expect to find "on a rocker." An elderly person, the stodgy old grandma or grandpa most every household has in residence (the expression dates from 1897, before nursing homes were so acceptable). Most of the time they just sit and rock, hands folded, muttering quietly. But every now and then a sudden agitation overcomes old Uncle Nancy, he jumps up and cavorts around the house. Or runs off to the wars with his WWII [actually, WWI] Home Guard helmet on-- "out of uniform" so to speak, like Hyacinth Bucket's old dad. [from the hilarious British sit-come "Keeping up appearances" - still re-run on some USA tele channels!]" - from source 2 below.

Unfortunately, none of your links seem to work. Which seems strange as you only posted them 45 minutes ago. I love the historical touches you have given to the story, and I would have up-voted your answer but for the broken links.
–
Mari-Lou AAug 7 '13 at 15:46

That's rather strange because I just tried those links straight from this page and they worked just fine. My boyfriend and I were debating the meaning and I found this well written answer on yahoo answers.
–
JacqieAug 7 '13 at 16:51

It is a term of the industrial revolution. A rocker arm is (was) used in internal combustion engines and in industrial looms. It is a fragile part of the machine. When the machine went "off its rocker" the machine had to be stopped immediately (not within seconds, that would be too long) or it would destroy itself and possibly those working around it.

It is helpful if you can provide some independent third-party support for your answer, such as other references that support your reason. This is always preferred on this site, but is particularly important in this case because your answer disagrees with other answers that do provide external references as support.
–
TrevorDJul 2 '13 at 18:41

I would assume that being off your rocker would refer to something similar to a rocking chair, always the same, predictable notion. But if the chair was off the rocker it would be unpredictable and free to act.

There are many nuances behind the saying, many of which have been touched upon above. The advance towards terminal old age has long been regarded as a time in which the individual resorts more and more towards resting and rocking in his/her rocking chair. So, in that regard, a rocking chair/rocker is normally seen as a place of sedate as well as dignified refuge. (Indeed, families would acquire rocking chairs for their palliative effects on parents of "rapidly contracting" years.)

The seeming contradiction (rocking or no longer rocking) comes about in the notion that decline into senile psychosis is a departure from sedate into frenzied rocking (just like a disturbed child's insistent, bounding, rocking on and of a rocking horse) to a point where all (physical and mental) equilibrium is lost--figuratively and literally, the point at which one has gone "off the trolley" (and onto a path no longer straight, no longer with rational destination).

The likeness implied in the notion of becoming separated from reality (where reality is the rocker, and to be active on the rocker, unreality to be active off the rocker) also alludes to the idea of "second childhood" (the process of age regression) often seen as part of the decline into advanced old age and mental deterioration, to wit, the syndrome of Alzheimer's disorder. Such regression, albeit typically far shorter lived, attends also to people retaining normal capacity for a lifetime, only to reveal itself--such as in baby-like references and appeals to "mamma"--as a near penultimate prequel to death (for those not reaching their ends in drug induces states).

All of that is not to say that "off one's rocker" is a saying confined to the aged. As the saying came more and more to be part of the English speaking lexicom, it also came to be generalized to a "more complete" spectrum of mental "suffering" or disturbance, even to those, young and old alike, whose real or perceived impairment falls far short of psychosis.

Off another's rocker also alludes, unlike off-trolly, to loss of time concept, of passage- of-time sensibility, as exemplified by the metrical rythm of motion, sight, and sound of rocking.

This is a very long post that cites not a single reference. Please back up some of your statements.
–
Mr. Shiny and New 安宇Oct 19 '12 at 13:14

1

This could've been summed up as follows: Old people use rocking chairs. Getting out of the chair ("off the rocker"), a metaphor for being active (perhaps excessively so), is traditionally out of character for old people. The phrase now applies to all ages. Your language obfuscates any meaningful addition, and none of it is sourced beyond your personal opinion. -1 :(
–
ZairjaOct 19 '12 at 21:03

I don't get it very well:except what I wrote. The metaphor is quite well known even if the illusion is not, beyond the life of any "here" and most if not all English speakers in existence. Had the Q asked since when I would not have posted. But is asked why rocking chair (as the metaphoric likeness). Perhaps the Q should be expanded (or reduced) to ask; how long have rockers (another "concept" also known to be a rockable seating facility) have been around...because before then people could not have spoken of on or off, in literal or metaphoric sense. Let me check into that...but I am doubtful.
–
lexOct 19 '12 at 22:16

A search for origin of rocking chair stumped the gooogle engine since the prior comment. Many with experience, even as much as 60 or more involving mental instablity, will have witnessed activity so uncharacterisic of the elderly is often the first alert that things are seriously wrong. Now I will see what google can provide as to the first incidence of frenzied rocking as prelude to separation from the rocker. Or the first documentation of its association with emotional disturbance in children. BTW illusion for allusion, above, is a type.
–
lexOct 19 '12 at 22:31